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The development of composites based on inorganic binders designed for the extreme applications
Janoušek, Petr ; Šácha, Libor (referee) ; Dufka, Amos (advisor)
The topic of this master's thesis is the development of composite materials based on inorganic binders for use in extreme conditions. It means especially geopolymeric or alkali activated materials (AAM) based composites. The theoretical part of this thesis summarizes knowledges about the development and use of alkali-activated materials, their structure and mechanisms of their formation. It also deals with the applicable raw materials for AAM and their exciters, which are in particular water glass and sodium hydroxide. There also have been a summary of the effects of high temperatures and chemicals on the mechanical properties of AAM and the requirements of standard EN 1504-3 for repairing materials. The task of the practical part was to develop a repair mortar for concrete structures based on AAM so that its production was as simple as possible, ie one-component materials. Gradually six recipes have been develeoped. Test specimens made from these recipes have been putted to selected tests according to the requirements of ČSN EN 1504-3.
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Comparison of environmental and technological properties of various methods of manufacture of foundry moulds and cores
Dlouhá, Monika ; Rusín, Karel (referee) ; Cupák, Petr (advisor)
The roots of foundry manufacture perhaps go back to 2000 BC. Since foundry production in its development has undergone four stages and each of them there was a qualitative jump. From 20 century, the chemicals used in foundry moulds and cores which is the cause producing harmful substances that have a negative impact on the environment. Major sources of harmful substances are just binders, hardeners and catalysts that are needed for bonding of moulding mixture. The third stage deals with the foundry physical processes that are not using today, even though they are most ecological. Nowadays the most used methods Cold-box, Warm-box and Hot-box.
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Study of synthetic sandstones preparation possibilities
Solik, Jaroslav ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
This thesis explores the possibility of developing synthetic sandstones based on alkaline-activated (geopolymer) binders. The goal is to design an appropriate connective system of optimal concentration, so that the prepared material (artificial stone) showed similar characteristics as natural. The experimental section summarizes the experiments that explore several different alkali connective systems. The aim is to compare the properties of binders prepared from methakaolin (Mefisto K-05 and L-05) alkali-activated by sodium or potassium water glass. For comparison with these connective systems were also prepared samples of commercially supplied geopolymer binder called Baucis
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Modern anorganic foundry binder systems
Kolařík, Martin ; Rusín, Karel (referee) ; Cupák, Petr (advisor)
This bachelor thesis deals with newly developed inorganic binder systems. These are mainly developed for their ecological advantages. However, some of the discussed binder systems have better technological properties. Inorganic binder systems are described herein, both on the basis of alkaline silicates and on the basis of inorganic salts. Attention is also paid to bentonite, which is still the most commonly used binder in the world. It turns out that these binder systems will be important for the future of the foundry industry.
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Possibilities of the utilization of the waste sand from the water glass production in building industry
Bílek, Vlastimil ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
Nowadays, the waste sands from the water glass production have no utilization and due to high alkali content are considered as a dangerous waste. So the aim of this thesis is to find and study some possibilities of their utilization in the building industry. First of all, some necessary analysis of these sands were performed and then some advantages and disadvantages of their application for production of materials based on portland cement and alkali activated materials were studied. Characteristics of fresh and hardened pastes, mortars and concretes containing these waste sands were determined. The most tested properties were their workability and their compressive and flexural strength. Close attention for the risks of alkali-silica reaction and for options of its suppressing by the mineral admixtures was paid.
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Changes of slag particles during its alkaline activation
Petrů, Ludmila ; Hrubý, Petr (referee) ; Bílek, Vlastimil (advisor)
This bachelor thesis deals with changes of slag particles during its alkaline activation. The altered parts of the slag as well as the course of the alkaline activation varies depending on the activator used, and therefore suspensions of blast furnace slag in sodium hydroxide, water glass, sodium carbonate and, for comparison, in water were prepared. Slag particles were isolated from these suspensions at selected time intervals (5 min, 30 min, 1 h, 2 h, 5 h and 24 h) for particle size analysis and evaluation of BET specific surface. After solidification, the microstructure of the samples was observed using an electron microscope. To better assess the reaction processes, the pore solution was isolated from the suspensions and its composition was analyzed using optical emission spectrometry in inductively coupled plasma. The hydration process was monitored using isothermal calorimetry.
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The development of composites based on alkali-activated matrices resistant to extreme temperatures
Ševčík, Marek ; Šácha, Libor (referee) ; Dufka, Amos (advisor)
The diploma thesis is focused on the development of composites from alkali activated materials (AAM) and their resistance to extreme temperatures. The theoretical part describes alkaline activation and precursors for the production of AAM. Furthermore, the problem of the effect of extreme temperatures on these materials is described. In the experimental part, the optimal silicate modulus with respect to the properties of AAM was gradually determined, and the effect of extreme temperatures on the AAM matrix was verified. In the next stage, the effect of the filler with respect to the behavior at extreme temperatures was tested and then the final formulation was optimized.
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Methodology for determining the chemical composition of water glasses
Flídrová, Michaela ; Bartoníčková, Eva (referee) ; Kalina, Lukáš (advisor)
The bachelor thesis deals with the methodology of determination of the chemical composition of water glasses. The aim was to find a more suitable method than the colorimetric analysis used by one of the domestic water glass manufacturers. The current procedure can be used to determine the content of Me2O (Na2O, K2O, Li2O), however, in the determination of SiO2 the method is inaccurate since the color change of the indicator during the second titration is very slow and therefore the equivalence point is ambiguous. The main aim of this work was to find a suitable method for the complex determination of the chemical composition of water glasses, which is compared with other methods used in the analytical chemistry of silicate materials. A very promising method is the conductometric titration with a volumetric hydrochloric acid solution, which provides an accurate, fast and instrumentally inexpensive method of chemical determination.
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Modern anorganic foundry binder systems
Kolařík, Martin ; Rusín, Karel (referee) ; Cupák, Petr (advisor)
This bachelor thesis deals with newly developed inorganic binder systems. These are mainly developed for their ecological advantages. However, some of the discussed binder systems have better technological properties. Inorganic binder systems are described herein, both on the basis of alkaline silicates and on the basis of inorganic salts. Attention is also paid to bentonite, which is still the most commonly used binder in the world. It turns out that these binder systems will be important for the future of the foundry industry.
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Study of shrinkage reducing admixture efficiency in alkali activated systems
Fojtík, Ondřej ; Koplík, Jan (referee) ; Bílek, Vlastimil (advisor)
Significant drying shrinkage is one of the major issues for the wider application of materials based on alkali-activated slag (AAS). Some shrinkage reducing admixtures (SRA) were developed for the ordinary portland cement systems. A couple of previous studies focused on the efficiency of these SRA in alkali-activated materials. The studies were mainly concentrated on the SRA based on polypropylene glycol. This thesis deals with efficiency of the SRA based on 2 methyl-2,4-pentanediol in AAS pastes and mortars. Influence of the SRA and activator (waterglass) dose on the drying shrinkage and other properties of AAS (flexural and compressive strength, autogenous shrinkage, workability, setting time and microstructure) were investigated. It was found, that at the activator dose when Na2O/slag mass ratio equals 4 or 6 %, SRA causes retardation of hydration, which leads to shrinkage reduction, however strength is reduced significantly, weight lost during the drying is increased and the coarsening of the pore structure occurs. At the activator dose when Na2O/slag mass ratio reaches 8, 10 or 12 %, in the presence of SRA the drying shrinkage is reduced, weight lost during the drying is similar to the reference, strength is increased and microstructure is unchanged against reference. It has been proved that SRA works properly in AAS only at higher activator doses.
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